Atadura

Helper tiny module to provide easy binding support as bind_quoted does for quote do.

Installation

def deps do
  [{:atadura, "~> 0.1"}]
end

Usage

The module providing easy binding for meta-generated modules. Use it as:

Example

require Atadura
Atadura.defmodule Circle, answer: 42, pi: 3.14 do
  def area(radius: r), do: 2.0 * pi * r
end
Circle.area(radius: 2)
#⇒ 12.56

Drawback: the compilation of modules, defined with Atadura will generate warnings like:

warning: variable "status" does not exist and is being expanded to "status()",
   please use parentheses to remove the ambiguity or change the variable name

I have no idea yet on how to suppress them, besides using status() for calling binded variables. Sorry for that.

To create a module with bindings, use Atadura.defmodule in place of plain old good defmodule. Whatever is passed as second parameter keyword list, will be available in the generated module in three different ways:

• as local functions,
• as module variables,
• as ~b|| sigil.

The module will be granted with bindings function, returning all the bindings as a keyword list.

Also, a “nested” module will be created for the generated module. It is named Parent.Module.FQName.Bindings, and is exporting following macros:

• bindings! to populate the bindings as local variables in the current context
• attributes! to populate the bindings as module attributes in the current context (NB: this macro is internally called to populate module attributes in the newly created module).

Examples

defmodule WithBinding do
  require Atadura
  Atadura.defmodule DynamicModule, status: :ok, message: "¡Yay!" do
    def response, do: [status: status, message: message]

    IO.inspect message, label: "Message (local)"
#⇒         Message (local): "¡Yay!"
    IO.inspect @message, label: "Message (attribute)"
#⇒         Message (attribute): "¡Yay!"
    IO.inspect ~b|status message|, label: "Message (sigil)"
#⇒         Message (sigil): [:ok, "¡Yay!"]
  end
end

WithBinding.DynamicModule.response()
#⇒ [status: :ok, message: "¡Yay!"]

Populating attributes:

require WithBinding.DynamicModule.Bindings
#⇒ WithBinding.DynamicModule.Bindings
WithBinding.DynamicModule.Bindings.bindings!
#⇒ [:ok, "¡Yay!"]
status
#⇒ :ok

Importing

import Atadura, only: [:defmodule, 3]

The above allows to still use default Kernel.defmodule/2 unless the keyword list is given as the second parameter:

import Atadura, only: [:defmodule, 3]

# Plain old good `Kernel.defmodule/2` without bindings
defmodule A1, do: def a, do: IO.puts "★★★"

# `Atadura.defmodule/3` with bindings
defmodule A2, [b: 42], do: def a, do: IO.puts "★★★"

Without explicit import, Atadura.defmodule/{2,3} would gracefully fallback to Kernel.defmodule/2 if no bindings were given.

Changelog

0.2.0 allow dynamic module names

Documentation

The docs, although everything is written above in this README, can be found at https://hexdocs.pm/atadura.